Logical Disk Manager - Basic Volumes and Dynamic Volumes

Basic Volumes and Dynamic Volumes

Dynamic volume is a Microsoft proprietary format developed together with Veritas (now acquired by Symantec). Basic volumes and dynamic volumes differ in ability to extend storage beyond one physical disk. The basic partitions are confined to one disk and their size is fixed. Dynamic volumes allow to adjust size and to add more free space either from the same disk or another physical disk. Dynamic volumes using space on different physical disks are called spanned volumes. Presently spanned volume can use a maximum of 32 physical disks.

The main differences between basic and dynamic disks are:

• Dynamic disks support multipartition volumes; basic disks do not.
• Windows stores basic disk partition information in the registry and dynamic disk partition information on the disk

Dynamic disks allow more flexible configuration without the need to restart the system. Some space at the end of the disk is reserved by Setup in case upgrading the disk to a dynamic disk is required. Dynamic disk information is saved at the end of the disk. The amount that is reserved is a minimum of one cylinder, or 1MB, whichever is greater. One cylinder can be up to 8MB (the reason why there is a remaining 8 MB unused partition every time windows setup is used to create a partition), depending on drive geometry and translation.

The operations common to basic and dynamic disks are the following:

• Check disk properties, such as capacity, available free space, and current status.
• View volume and partition properties, such as size, drive-letter assignment, label, type, and file system.
• Establish drive-letter assignments for disk volumes or partitions, and for CD-ROM devices.
• Establish disk sharing and security arrangements for a volume or partition.
• Upgrade a basic disk to dynamic, or revert a dynamic disk to basic.